The present invention relates generally to protection circuits and particularly is concerned with such a circuit useful in conjunction with multiplexed vehicle control systems such as the one disclosed in U.S. Pat. No. 3,648,057, issued to Peter W. Sognefest et al and assigned the same assignee as the present application.
Vehicular control and distribution systems such as the one disclosed in the Sognefest et al patent have generally included a receiver circuit which actuates one or more load devices upon receipt of the proper input information. The receiver circuit, upon receipt of the proper input information, provides a continuous output command signal which energizes a semiconductor switch located in series with the electrical load device to actuate it.
In the past is has happened, much more often than desired, that a short has occurred across the load device, thus placing the entire supply voltage across the semiconductor switch. Inasmuch as the semiconductor switch is not designed to handle the excessive currents brought about by the short circuit condition at the load, it is eventually destroyed, resulting in the added inconvenience of replacing the semiconductor switch as well as correcting the short circuit condition at the load. This procedure, of course, results in the added time and labor necessary to replace the semiconductor switch as well as the cost of the switch itself.